Mobility and availability to plants of two zinc sources applied to a calcareous soil

The objective of this study was to compare the migration, availability, and relative effectiveness of Zn from liquid Zn-amino acids (Zn-AA) and Zn-DTPA-HEDTA-EDTA (Zn-CH: DTPA, diethylenetriaminepentaacetate; HEDTA, N-2-hydroxyethyl-ethylenedinitrilotriacetate; EDTA, ethylenedinitrilotetraacetate) sources by applying different Zn levels to a calcareous soil in incubation, column, and greenhouse experiments. Zinc soil behavior was evaluated by sequential fractionation, and DTPA and Mehlich-3 extractions. The results of the incubation study showed that amounts of Zn in the most labile fraction (water soluble plus exchangeable) were detected only when Zn-CH fertilizer was applied. A large portion of Zn applied to soil occurred in the amorphous Fe oxide bound fraction in all fertilization treatments. The results of the column study showed that addition of Zn-CH resulted in greatly increased mobility of Zn through the column as compared with the control and the Zn-AA source, and 49% of Zn applied as Zn-CH was leached from the column. The results of the greenhouse study showed in the absence of leaching that the application of two Zu sources significantly increased maize (Zea mays L.) dry matter yield compared with the control treatment although the increase in the Zn dosage did not increase dry matter further. The fertilizer treatments also significantly increased Zn concentration in plants, except the lowest dosage of Zn-AA. Zn-CH was more effective than Zn-AA. The differences in plant Zn uptake in the greenhouse experiment between two Zn sources was correlated with the water soluble plus exchangeable fraction and DTPA extractable Zn in the incubation experiment.